14 Teel FISH BULL 101(3)

Genetic analysis of juvenile coho salmon (Oncorhynchus kisutch) off Oregon and Washington reveals few Columbia River wild fish Item Type article Authors Teel, David J.; Van Doornik, Donald M.; Kuligowski, David R.; Grant, W. Stewart Download date 30/09/2021 19:04:38 Link to Item http://hdl.handle.net/1834/31006 640 Abstract—Little is known about the Genetic analysis of juvenile coho salmon ocean distributions of wild juvenile coho salmon off the Oregon-Washington (Oncorhynchus kisutch) off Oregon and coast. In this study we report tag recoveries and genetic mixed-stock estimates Washington reveals few Columbia River wild fi sh* of juvenile fi sh caught in coastal waters near the Columbia River plume. To sup- David J. Teel port the genetic estimates, we report an allozyme-frequency baseline for 89 Donald M. Van Doornik wild and hatchery-reared coho salmon David R. Kuligowski spawning populations, extending from Conservation Biology Division northern California to southern Brit- Northwest Fisheries Science Center ish Columbia. The products of 59 allo- 2725 Montlake Boulevard East zyme-encoding loci were examined with Seattle, Washington 98112-2097 starch-gel electrophoresis. Of these, 56 Present address (for D. J. Teel): Manchester Research Laboratory loci were polymorphic, and 29 loci had 7305 Beach Drive E. P levels of polymorphism. Average 0.95 Port Orchard, Washington 98366 heterozygosities within populations Email address (for D. J. Teel): [email protected] ranged from 0.021 to 0.046 and aver- aged 0.033. Multidimensional scaling of chord genetic distances between sam- W. Stewart Grant ples resolved nine regional groups that were sufficiently distinct for genetic P.O. Box 240104 mixed-stock analysis. About 2.9% of the Anchorage, Alaska 99524-0104 total gene diversity was due to differences among populations within these regions, and 2.6% was due to differences among the nine regions. This allele-frequency data base was used to estimate Nearshore and riverine distributions the fi rst to use genetic data to estimate the stock proportions of 730 juvenile coho salmon in offshore samples col- of maturing Pacifi c salmon (Oncorhyn- the stock origins of ocean mixtures of lected from central Oregon to northern chus spp.) are well known, largely juvenile coho salmon (O. kisutch). Washington in June and September- because of the prevalence of salmon One goal of our study was to cre- October 1998−2000. Genetic mixed- fi sheries and the tremendous amount ate a baseline of allelic frequencies in stock analysis, together with recoveries of information gathered to manage spawning populations of coho salmon of tagged or fi n-clipped fi sh, indicates these fi sheries. Out-migration timings throughout the Pacifi c Northwest and that about one half of the juveniles and abundances of smolts in streams California. These data were previously came from Columbia River hatcheries. as they migrate to the sea are also well used by the National Marine Fisheries Only 22% of the ocean-caught juveniles known, but information on the distribu- Service (NMFS) to defi ne evolutionarily were wild fi sh, originating largely from tions and stock origins of wild juveniles signifi cant units (ESUs) for evaluation coastal Oregon and Washington rivers (about 20%). Unlike previous studies in marine waters has been limited by under the Endangered Species Act of tagged juveniles, both tag recoveries two factors. The fi rst is that a large (Johnson et al., 1991; Weitkamp et al., and genetic estimates indicate the pres- amount of effort is needed to sample 1995). In the present study, we examine ence of fi sh from British Columbia and marine-phase juveniles, which gener- levels of variability among populations Puget Sound in southern waters. The ally occur at low densities (Godfrey, and use mixed-stock simulations to as- most salient feature of genetic mixed 1965; Hartt and Dell, 1986; Orsi et al., sess the usefulness of such a data set stock estimates was the paucity of wild 2000). The second factor is that stock as a baseline for genetic mixed-stock juveniles from natural populations in origins have been determined only for analysis. A second goal was to use this the Columbia River Basin. This result coded-wire−tagged (CWT) hatchery baseline of population data to estimate refl ects the large decrease in the abun- fi sh (e.g. Pearcy and Fisher, 1988; Orsi the stock compositions of juvenile coho dances of these populations in the last few decades. et al., 2000). Because only small propor- salmon collected in the early and late tions of hatchery juveniles are tagged, summers of 1998, 1999, and 2000 off samples of ocean-caught salmon are the Oregon and Washington coasts by largely a mixture of hatchery and wild the NMFS (Emmett and Brodeur, 2000). fi sh of unknown stock origins. Genetic We use a standard approach to genetic mixed-stock analysis, although used mixed-stock analysis that yields propor- routinely to estimate the stock compo- tional estimates of stock origin of fi sh sitions of mature returning salmon (e.g. in a mixed-stock sample (e.g., Pella and Manuscript approved for publication Milner et al., 1985; Shaklee et al., 1999; Milner, 1987). We compare early and 15 January 2003 by Scientifi c Editor. Beacham et al., 2001), has not been Manuscript received 4 April 2003 at fully exploited to estimate stock origins * Contribution 388 to the U.S. GLOBEC pro- NMFS Scientifi c Publications Offi ce. of immature salmon (but see Guthrie et gram, Woods Hole Oceanographic Institute, Fish. Bull. 101:640–652 (2003). al., 2000). The study we describe here is Woods Hole, MA 02543. Teel et al.: Genetic analysis of juvenile Oncorhynchus kisutch 641 late summer samples to detect seasonal shifts in stock 128° 124° 122°W compositions along the coast and make comparisons with 126° earlier tag-recovery studies to search for decadal shifts British Columbia in the marine distributions of particular stocks. Recent efforts at Pacifi c Northwest hatcheries to mark the major- r e ity of their releases of coho salmon with a fi n clip provide v i 50N° R new opportunities to estimate proportions of hatchery and r e 88 s 89 a wild coho salmon in ocean samples (Beamish et al., 2000; r F Lawson and Comstock, 2000). We therefore report genetic 86 87 85 estimates for hatchery-marked and unmarked fi sh in ocean 83 samples and use these estimates to identify hatchery and 84 82 63 75-81 wild population origins of ocean juvenile coho salmon. 73-74 La Push +++++ 59-62 64 57-58 65 70-72 66-68 69 Materials and methods +++++ +++++ 53-56 Location of +++++ 50-52 Washington To establish an allele-frequency baseline, populations of coastal pelagic 46° 34-37 38-39 coho salmon were sampled from 89 hatcheries, streams, trawl surveys +++++ 32-33 40-42 Columbia and rivers between 1984 and 1999 (Fig. 1, Table 1). Samples ++++ 31 43-49 River of skeletal muscle, eye, liver, and heart tissues were col- ++++ 30 lected from adults during spawning operations in hatcher- ++++ 26-29 ies or from whole juvenile fi sh in hatchery rearing ponds. 23-25 Cape Perpetua All hatchery broods sampled were the progeny of al least +++ 21-22 50 adult fi sh. Wild juveniles were sampled in natal streams 17-20 and rivers by electroshocking. Wild adult fi sh were sampled 11-16 Oregon in spawning areas by gaffi ng and dip-netting. 10 9 8 r ive Samples of juvenile coho salmon in marine waters were R 7 Rogue collected during NMFS coastal pelagic trawl surveys 42° (Emmett and Brodeur, 2000). Trawls consisted of one- 5 h r t Rive half-hour long surface tows with a 264 Nordic rope trawl a m a l along nine transects perpendicular to shore ranging from K La Push, Washington (47°55′N) to Cape Perpetua, Oregon 4 (44°15′N) (Fig. 1). Sampling stations began 1−5 nautical 6 California miles offshore and continued, in about 5 nautical-mile r e v (nmi) increments, to about 30 nmi offshore. Marine ju- i R veniles were sampled 16−24 June and 21−30 September o t 3 n 1998, 16−24 June and 21 September−1 October 1999, and 2 e m a r c 17−25 June and 19−24 September 2000. Fish were mea- a N S sured and examined for the presence of fi n clips and coded 38° wire tags (CWTs). Juveniles in their fi rst ocean summer were separated from older coho salmon by length by using a modifi cation of the criteria of Pearcy and Fisher (1990). 1 Fish with fork lengths less than 330 mm (June) and 450 0 100 200 km mm (September–October) were considered to be juveniles in their fi rst year in the ocean. Fish with CWTs, and therefore of known brood year, provided supporting evidence for Figure 1 these criteria with the assumption that growth of hatchery Locations of ocean sampling transect lines (+) and 89 coho salmon and wild fi sh was similar. populations in California, Oregon, Washington, and British Colum- bia. Numbers correspond to population names in Table 1. Tissue samples or whole juvenile fi sh were frozen on dry ice or in liquid nitrogen and stored at −80°C prior to electrophoretic analysis. We used the methods of Aeber- sold et al. (1987) for sample preparation and horizontal Genotypic frequencies of polymorphic loci for each base- starch-gel protein electrophoresis. Electrophoretic condi- line sample were examined for departures from expected tions for 30 enzymes, for which we obtained reliable and Hardy-Weinberg proportions with a Fisher’s exact test interpretable data for 59 loci, are reported in an appendix (Guo and Thompson, 1992) by using GENEPOP version that can be retrieved at the Northwest Fisheries Science 3.1 (Raymond and Rousset, 1995).

Load more